As a medical laboratory technician,
I have learned that accuracy and efficiency in laboratory testing are essential
virtues for the process of clinical diagnosis. The faster a physician gets
results, the faster an effective differential can be performed. This not only
leads to quality care for the patient, but can even mean the difference between
life and death. As the medical technology industry expands, and the
communication network between clinical sites become more efficient, patients
have greater chances for survival, even when they are facing some of the most
horrifying situations.
The following is a comparison of
two case studies involving the same pathogen, Naegleria fowleri. Case One, taken from an article in Clinical Infectious Diseases, involves a
four-year-old boy in Louisiana(1). Case Two, taken from an article in PEDIATRICS, involves a twelve-year-old
girl in Arkansas(2). Both cases begin in the middle of July, 2013.
The symptoms:
In the case of the four-year-old
boy, symptoms began to present as vomiting and headache with a fever of 104
degrees F. Two staring spells occurred in which the boy was non-responsive for
several seconds at a time before returning to normal. After the second
occurrence, the boy was brought into the New Orleans emergency department.
There, a third occurrence of staring was observed. The boy’s vitals were all
within normal ranges. His headaches persisted until day three, when he began to
suffer hypertension, slowed heartbeat, and multiple seizures. (1)
For the case of the twelve-year-old
girl, symptoms also presented as severe headaches over two days. On the second
say, a fever of 103 degrees F also presented, along with nausea and vomiting.
She was admitted to the Arkansas Children’s Hospital where her condition
worsened. On day three she developed right-sided abducens nerve palsy -the
inability to turn her eye outward. (2)
According to the CDC, early
symptoms of infection by Naegleria
fowleri include severe frontal headaches, fever, nausea and vomiting. This
was seen in both cases above and unfortunately, are not very specific
indications as to what may be the cause. These symptoms appear about five days
after exposure to the ameba and are likely attributed to immune response to the
infection. Late symptoms occur only days after the first set of symptoms
present. These new symptoms include stiff neck, seizures, altered mental
status, and eventually coma and death. Naegleria
fowleri is a free-living ameba that lives in warm freshwater, including
lakes, swamps, and streams. It is motile in this stage and feeds on bacteria in
the water. When it comes in contact with a human through their nose, it will
make it’s way toward the brain. Here, it causes Primary meningoencephalitis(PAM)
as it feeds on brain tissue. (3)
The Clinical
Development:
During
the boy’s second day of symptomatic presentation, his CT scan presented normal,
while both his blood and cerebral spinal fluid(CSF) showed elevated levels of
white blood cells(WBC). A brain scan on day three showed signs of edema. By day
four, there was no longer any electro-cerebral activity. (1)
In
the girl’s case, she too had a normal CT scan upon first arrival at the
hospital. Like the boy, her white blood cells were also elevated. The CSF from
her lumbar puncture was examined for infection, where the ameba Naegleria was
identified. A sample was sent to the CDC for further confirmation. On day two,
she developed intracranial pressure due to edema, which worsened by day three.
(2)
Infection
with Naegleria fowleri is very
dangerous and it can be difficult to diagnose due the non-specific presentation
of symptoms. Generally, observation of ameba in the CSF is the fastest and only
current way to rule out similar possibilities such as bacterial meningitis.
Confirmation through a reference lab, such as the CDC, helps to focus treatment
as speed seems to be key for a better prognosis. The alternative way to confirm
infection by Naegleria fowleri has
traditionally been by autopsy after the patient has passed. Since 1962, 132
cases of PAM by Naegleria fowleri
have been recorded with only 4 survivors across North America. (2)
The Treatment:
The
boy was first given acetaminophen by the mother when symptoms first developed,
which had no effect. At the hospital, he was administered Vancomycin and
ceftriaxone to treat any possible bacterial meningitis. After seeing elevated
WBC count in the CSF, piperacillin–tazobactam and acyclovir were administered. When signs of edema
in the brain showed on day three, the boy was put in an induced coma and
treated with hyperosmolar therapy to reduce pressure in the brain.
Unfortunately, symptoms worsened, and by day five the family chose to remove
life support. (1)
When the laboratory in
Arkansas reported possible Naegleria infection in the girl’s CSF, she was
placed on amphotericin, fluconazole, rifampin, azithromycin, and dexamethasone.
On her second day of hospitalization, the CDC confirmed the infection of Naegleria fowleri and she was treated with hyperosmolar
therapy and induced hypothermia. She was also started on miltefosine. The
treatment regimen was sustained for nearly a week, while daily CSF monitoring
showed a steady reduction in infectious load. The girl recovered from edema
after two weeks and finished the rehabilitation and antibacterial treatment by
day fifty-five. She was able to return to school soon after. (2)
According to an article by Travis
Heggie, Naegleria fowleri has been
found in places all around the globe, including Japan, Australia, England, and
Italy(4). As a free-living ameba, it is able to live in the soil, although it
prefers warm liquid environments. Most often, infection occurs when someone
goes swimming and inhales the contaminated water. Symptoms may not arise for up
to nine days after infection, leading investigators to search multiple habitats
the individual may have visited since. In the case of the boy in Louisiana,
investigators determined that contamination came from the tap water, likely due
to poor conditions post hurricane Katrina(1).
The CDC’s recommended treatment for
Naegleria fowleri infection includes
a combination of antimicrobials and aggressive management of acute symptoms.
The most important thing to increase odds of survivability seems to be the
speed of diagnosis, leading to immediate treatment. Naegleria fowleri acts fast, and the damage it causes is quickly
fatal. The CDC now holds a stock of miltefosine as an investigational drug to
help fight off infection. Meanwhile, fluid buildup and inflammation in the
brain needs to be reduced through hyperosmolar and hypothermic therapies. These
therapies pull the fluid back into circulation, away from the brain, and slow
the progression of the ameba until the medication and the body’s immune system
can fight back. After the infection clears, the body still needs time to
recover from the trauma, often requiring physical therapy. (3)
References:
1)
Cope, Jennifer R. et al. “The First Association of a
Primary Amebic Meningoencephalitis Death with Culturable Naegleria Fowleri in
Tap Water from a US Treated Public Drinking Water System.” Clinical
Infectious Diseases 60 (2015): e36–e42. Web.
2)
Linam, W M et al. “Successful Treatment of an
Adolescent with Naegleria Fowleri Primary Amebic Meningoencephalitis.” Pediatrics
135.3 (2015): e744–8. Web.
3)
“Naegleria Fowleri — Primary Amebic Meningoencephalitis
(PAM) — Amebic Encephalitis.” Centers for Disease Control and Prevention.
Accessed November 5-9, 2016. Web. <http://www.cdc.gov/parasites/naegleria/illness.html>.
4)
Heggie, Travis W. “Swimming with Death: Naegleria
Fowleri Infections in Recreational Waters.” Travel Medicine and Infectious
Disease 8.4 (2010): 201–206. Web.
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